Ruger AR UPPER RECEIVER ASSEMBLED - 91003 - 736676910038
Product Description
Building a reliable custom AR-15 upper from completely bare, stripped components can introduce assembly bottlenecks, such as installing finicky roll pins, small springs, and retaining clips for forward assists and dust covers. Out-of-spec upper receivers can cause bolt carrier binding, misalignment with lower receivers, or loose barrel nut thread tolerances. The Ruger Factory Assembled AR Upper Receiver (91003) eliminates these setup headaches by delivering a precision-machined, factory-assembled receiver shell complete with the dust cover and forward assist assemblies pre-installed.
Forged from high-strength 7075-T6 aluminum and finished in a durable Type III Class 2 hardcoat anodized matte black coating, this factory upper receiver features M4 feed ramps precision-machined prior to anodizing to ensure seamless cartridge feeding from magazine to chamber. Machined to standard Mil-Spec dimensions, it features a full-length top Picatinny rail with laser-engraved T-marks for consistent optics and accessory staging.
Ideal for custom rifle builds, caliber conversions, or replacing worn upper receivers, the Ruger 91003 assembled upper receiver provides genuine OEM factory durability, precise receiver alignment, and a solid foundation for your next AR-15 project.
*Armorer Bench Notes & Real-World Staging Guidance:
Fitment & Compatibility Matrix: Direct compatibility with standard Mil-Spec AR-15 / M4 lower receivers and standard AR-15 barrel extensions featuring M4 feed ramps. Designed for standard 0.250" takedown and pivot pin holes. Note: Bolt carrier group (BCG), charging handle, barrel, and handguard are sold separately.
Installation & Assembly Sequence:
- Safety check the workspace and verify all components are clean and free of metal shavings.
- Apply a liberal coat of aerosol grease (AeroShell 64 / 33MS) to the upper receiver barrel extension threads.
- Insert your barrel extension into the receiver socket, ensuring the extension pin aligns cleanly with the upper receiver top notch.
- Thread the barrel nut onto the receiver and torque using an armorer's wrench according to barrel manufacturer specs (typically 30–80 ft-lbs).
- Install the gas tube and handguard system, then slide in a Mil-Spec bolt carrier group and charging handle to complete manual cycling checks before live fire.
Key Features
- Factory Pre-Assembled Hardware: Comes complete with the forward assist and ejection port dust cover pre-installed from the factory.
- Forged 7075-T6 Aluminum Construction: Offers maximum structural integrity to withstand high chamber pressures and heavy duty use.
- Precision Machined M4 Feed Ramps: Ensures smooth, reliable round feeding from magazine to chamber without bullet nose deformation.
- Mil-Spec Hardcoat Anodized Finish: Type III matte black hardcoat protects against abrasion, chemical solvents, and corrosion.
- Laser-Engraved T-Marked Top Rail: Flat-top Picatinny rail includes clear slot markings for precise, repeatable sight and optic indexing.
Product Specifications
- Brand: Ruger (Sturm, Ruger & Co.)
- Model: AR-15 Assembled Upper Receiver
- MPN: 91003
- UPC: 736676910038
- Platform Compatibility: Standard Mil-Spec AR-15 / M4 / AR-556
- Material: 7075-T6 Forged Aluminum
- Feed Ramps: M4 Feed Ramps
- Finish / Color: Matte Black Hardcoat Anodized
- Included Components: Upper Receiver Body, Ejection Port Cover Assembly, Forward Assist Assembly
